Definition. Fugacity can be defined as the tendency to escape. It is measured in Pa because is the force applied by the molecules to escape to other phase per area.
Gpf = Gpi + RT ln (Fi / Plow)
Considerations:
If Fi = P there is Ideality.
Fugacity coefficient:
For ideality: Fugacity coefficient = 1 As we can see that for low pressure the ideal and the real behavior the same.
Now we will proceed to explain different cases of fugacity and a real life example called fugacity in lakes, clic on the button below or in other topic of your interest